3)Using interactions between colloidal particle
Because thermal energy allows particles to explore phase space and achieve the lowest-energy structure, the thermalization of the particles in response to Brownian motion is essential to allowing them to self-assemble. <math>k_B T</math>

Main Obstacle

The surface energy drives the interface of the particle to be spherical, which places fundamental limitations on the structures that can be built.An important limitation comes in making photonic-bandgap structures